International Humic標(biāo)準品代理

IHSS于1981年9月11日在美國科羅拉多州丹佛市成立，旨在匯集煤炭、土壤和水科學(xué)領(lǐng)域?qū)Ω澄镔|(zhì)感興趣的科學(xué)家。IHSS擁有近900名科學(xué)家。在促進科學(xué)教育和研究以及促進公眾對腐殖物質(zhì)的了解方面，學(xué)會被gong認為世界領(lǐng)dao者。IHSS的座右銘是：“推進土壤和水中天然有機物的知識和研究"。該協(xié)會的目標(biāo)包括建立和維持從褐煤、淡水、礦物土壤和有機土壤中收集腐殖酸和黃腐酸的標(biāo)準樣品，以及收集表征數(shù)據(jù)。此外，協(xié)會還增加了作為研究腐殖物質(zhì)來源的參考樣品。IHSS每兩年召開一次國際會議，匯聚來自土壤、煤炭、淡水和海洋科學(xué)的科學(xué)家。這些會議由主要科學(xué)家與IHSS委員會合作召開。

International Humic標(biāo)準品代理

，International Humic產(chǎn)品列表：

Cat. No.	Source	Carboxyl	Phenolic	Q1	Log K1	n1	Q2	Log K2	n2	N	RMSE
Sources: (1) School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, U.S.A.; (2) Department of Chemistry, Environmental Sciences Ph.D. Program, Ball State University, Muncie, IN, U.S.A.
References: (1) J. D. Ritchie and E. M. Perdue, Geochim. Cosmochim. Acta, 67, 85-96 (2003); (2) S. J. Driver and E. M. Perdue, Advances in the Physicochemical Characterization of Dissolved Organic Matter: Impact on Natural and Engineered Systems, American Chemical Society, 1160: 75-86 (2014).
Solutions containing 0.36 ± 0.01 g L-1 (on a dry ash-free basis) of an IHSS sample in 0.1 M NaCl were titrated from their initial pH values of 3.0-3.3 to final pH values of 10.5-10.7 in 25-35 minutes, using 6-8 mL increments of carbonate-free 0.100 M NaOH. All titrations were conducted under a N2 atmosphere in a thermostated water bath at 25.00 ± 0.02 °C. At least three titrations were obtained for each sample. The stock solutions of soil, peat, leonardite, and Summit Hill humic acids also contained 0.002 M NaOH, which was needed to effectively disperse/dissolve those samples, and an equivalent quantity of HCl that was added just before a titration was started.
Carboxyl is the charge density (meq/g C) at pH 8.0; Phenolic is two times the change in charge density (meq/g C) between pH 8.0 and pH 10.0.
The overall charge density (in meq/g C) of a humic substance increases systematically with pH (or with the concentration of H+). The equation on the right, known historically as a modified Henderson-Hasselbalch equation for two classes of binding sites, was used to fit titration data and obtain the set of model fitting parameters in this table.
The fitting parameters of the model were obtained by a nonlinear least-squares fit of the model to aggregated sets of replicate titration data. Q1 and Q2 are the maximum charge densities of the two classes of binding sites, Log K1 and Log K2are the mean log K values for proton binding by the two classes of sites, and n1 and n2 are empirical parameters that control the width (in log K) of a class of proton binding sites. N is the number of fitted titration data points, and RMSE is the root mean-square error for fitting this model to the data (see Reference). This model, also known in more recent literature as a Langmuir-Freundlich equation, is the primary building block of the NICA class of models.
An * means that a sample is no longer available, and nd means that an item was not determined.
Standard HA
Suwannee River I *	1S101H	(1)	9.59	4.24	10.69	4.42	3.79	2.28	9.68	1.11	113	0.0673
Suwannee River II	2S101H	(1)	9.13	3.72	9.74	4.35	3.30	4.48	10.44	1.73	171	0.0815
Elliott Soil	1S102H	(1)	8.28	1.87	8.90	4.36	3.16	0.85	9.80	1.00	169	0.0943
Pahokee Peat	1S103H	(1)	9.01	1.91	9.64	4.22	3.20	0.94	9.86	1.00	145	0.0865
Leonardite	1S104H	(1)	7.46	2.31	8.17	4.59	3.32	1.13	9.72	1.31	106	0.0532
Standard FA
Suwannee River I	1S101F	(1)	11.44	2.91	12.00	3.80	3.21	1.48	9.52	1.00	109	0.1053
Suwannee River II	2S101F	(1)	11.17	2.84	11.66	3.76	3.24	2.05	9.84	1.45	123	0.1072
Elliott Soil I *	1S102F	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Elliott Soil II	2S102F	(1)	13.24	2.27	14.12	3.67	3.62	0.74	9.53	1.00	111	0.1375
Pahokee Peat I *	1S103F	(1)	13.34	2.32	14.22	3.99	3.33	0.76	9.57	1.00	117	0.1028
Pahokee Peat II	2S103F	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Reference HA
Suwannee River *	1R101H	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Pahokee Peat	1R103H	(1)	8.87	2.05	9.54	4.26	3.25	1.01	9.85	1.00	117	0.0773
Nordic Lake	1R105H	(1)	9.06	3.23	10.32	4.32	4.22	1.64	9.89	1.11	105	0.0740
Summit Hill Soil	1R106H	(1)	7.14	2.42	7.53	4.47	3.12	1.31	9.23	1.57	106	0.0480
Waskish Peat	1R107H	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Reference FA
Suwannee River	1R101F	(1)	12.23	3.11	12.94	3.81	3.36	1.60	9.62	1.00	115	0.1312
Pahokee Peat *	1R103F	(1)	15.24	1.78	16.25	3.73	3.54	1.31	10.74	1.00	129	0.1586
Nordic Lake	1R105F	(1)	11.16	3.18	12.15	3.79	3.95	1.49	9.67	1.00	107	0.1121
Waskish Peat	1R107F	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Pony Lake FA	1R109F	(2)	7.09	1.75	6.91	4.52	1.92	1.43	9.48	1.77	1256	0.0340
Aquatic NOM
Suwannee River I	1R101N	(1)	9.85	3.94	10.57	3.94	3.60	2.61	9.74	1.19	112	0.0725
Suwannee River II	2R101N	(2)	11.21	2.47	11.20	4.16	3.44	1.60	9.99	1.03	1705	0.1360
Nordic Lake	1R108N	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Upper Mississippi River	1R110N	(2)	12.43	0.83	12.51	3.47	2.69	0.91	10.00	1.00	1626	0.0800
Bulk Materials
Elliott Soil	BS102M	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Pahokee Peat	BS103P	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd
Leonardite	BS104L	(1)	nd	nd	nd	nd	nd	nd	nd	nd	nd	nd